Which is a drop in the ocean as far as the FOSS app ecosystem go, and to be honest after all this time I can't see either of GTK or Qt winning the 'toolkit war'.
If either of those would have the capacity to emerge as the de facto standard then it would have happened long time ago in my opinion.
Taking a quick look at the gui software (not a whole lot as I typically prefer the commandline) I have on my Linux desktop machine (running bspwm, not a desktop environment):
Of course this is purely anecdotal, but this notion of some 'winner' in the FOSS toolkit space comes across as fanboyism more than anything based in reality.
I'm not citing Qt software I use, I'm citing GTK software that is now switching toolkits. How many apps are going from Qt to GTK? I could write a list of KDE equivalents to all the GTK programs you are citing - nobody is arguing that there isn't pretty much a program for every use case written against either toolkit. The question is what is software people are using, and what toolkit are people looking to write new software using? Conclusively it seems to be Qt nowadays.
It's irrelevant how many apps are switching, given that Qt have for so many years been a total non-starter for a huge segment of Linux desktop apps. As you say, the question is what software people are using, and you've given nothing real to support your contention that this "conclusively seems to be Qt nowadays".
If either of those would have the capacity to emerge as the de facto standard then it would have happened long time ago in my opinion.
Taking a quick look at the gui software (not a whole lot as I typically prefer the commandline) I have on my Linux desktop machine (running bspwm, not a desktop environment):
Of course this is purely anecdotal, but this notion of some 'winner' in the FOSS toolkit space comes across as fanboyism more than anything based in reality.